Electric fuses for projectiles



9 1967 J. VILBAJO ELECTRIC FUSES FOR PROJECTILES 2 Sheets-Sheet 1 Filed Sept. 22, 1964 INVENTOR. J. VL'Z bczjo BY Arroruuess March 14, 1967 VILBAJO ELECTRIC FUSES FOR PROJECTILES 2 Sheets-Sheet 2 Filed Sept. 22, 1964 INVENTOR. V. 6a '0 BY J J ATTQILNEESS United States Patent Office 3,308,761 Patented Mar. 14, 1967 3,308,761 ELECTRIC FUSES FOR PROJECTILES Jean Vilbajo, Brussels, Belgium, assignor to Contigea Societe Anonyme, Brussels, Belgium Filed Sept. 22, 1964, Ser. No. 398,322 Claims priority, application Belgium, Sept. 30, 1963,

' 637,973; Aug. 31, 1964, 652,467

4 Claims. (Cl. 102-702) The more and more frequent use of electric fuses for common ammunition comprises serious problems of electrical connections.

In fact, the electric detonator must be short-circuited during storage and connected to the generator for firing.

It follows therefrom that the electrical connections must be absolutely reliable, considering that they must guarantee both the safety and the proper operation.

Considering that, most of the time, the detonator is outside the pyrotechnic alignment, it must be displaced when the shot is fired and the electrical connections are therefore secured by moving contacts, i.e. by devices whose reliability does not exceed 95%.

The object of the present invention is to provide an improvement of electric fuses for projectiles belonging to the type with a permanent pyrotechnic chain comprising at least one charge, one detonator and one fuse, this improvement consisting in introducing into aforesaid fuse means for ensuring disalignment at least between aforesaid fuse and aforesaid detonator, and means for reestablishing this alignment when firing.

The advantages resulting from such disposition are particularly important. In fact, the danger attending the handlingof projectiles or elements is essentially dependent on the nature of the pyrotechnic substances of which the fuse is built, the object of the latter being to convert a mechanical or electrical impulse into a detonating wave by means of a priming system which should be as sensitive as possible.

Due to the fact that the fuse and the detonator are separated, according to the present invention, the most dangerous element of a projectile is rendered less powerful, which considerably limits the risks and consequences of accidents.

On the other hand, the improvements disclosed by the present invention do away with the necessity of using fuse/detonator aggregates and thus also do away with the risks attending the manufacture of the latter. In fact, this classical process involves the setting of a fuse/detonator, which is always a source of danger because this aggregate contains substances which are likely to explode by shock.

The improvements according to the present invention I can be embodied in a large variety of forms.

It is thus merely by way of illustration that an example of embodiment, implying no limitation however, is described below with reference to the appended drawings, of which:

FIGURE 1 illustrates a radial section of an improved electric fuse in its state of rest;

FIGURES 2, 3, 4 and respectively illustrate sections by planes whose traces follow the straight lines IIII, III-III, IVIV, V-V of FIGURE 1;

FIGURES is a view along arrow P6 of FIGURE 1;

FIGURE 7 is a view similar to that of FIGURE 1, in

which however the fuse is illustrated in the cocked position;

FIGURE 8 is a section by a plane whose trace follows the straight line VIII-VIII of FIGURE 7.

In this form of embodiment, the electric fuse is represented by a hollow body 1 shaped externally so as to make it possible to fasten it at the height of the junction between the body and the chain of the projectile or in any other appropriate position. 7

Inside, the body is divided into two chambers 23 by an intermediate partition 4 which itself has a chamber 5 communicating with aforesaid chambers 2 and 3.

Towards the front, aforesaid hollow body 1 has an inner screw thread 6 into which is screwed a ring 7 which, in turn, is provided with an inner screw thread 8 into which is screwed the container 9 of a charge 10 which is part of the pyrotechnic chain for firing the projectile.

In the intermediate chamber 5 there is a priming system 11 which, according to one of the main features of the invention, is fixed. It is housed in a case 12 of conducting material. The aXis 13 of this priming device passes through an insulating partition 14 lining the adjacent bottom of aforesaid chamber 3 and bears against a little metal plate 15 resting onto aforesaid insulating material 14.

The only metal contact of the priming system 11-13 thus consists of aforesaid little plate 15 which, in the position of rest of the fuse, makes straight contact with the collar 16 of a rod 17 which is permanently acted upon by a return spring 18. This rod penetrates by one of its ends into aforesaid chamber 2 and forms a stop for a drum 19. The latter is housed in aforesaid chamber 2, has a cross-section of triangular shape and is mounted with an easy fit on a fixed axis 20.

Right through this drum there is a cylindrical hole 21 into which is fastened the detonator 22, according to another main feature of the present invention.

This detonator is thus moveable whilst aforesaid priming system 11 is fixed. Aforesaid drum 19 has on its periphery a notch 23 and is constantly urged toward its cocked position by a spring 24 wound about part of the 7 axis 20 in such way that one of its ends bears against the inner wall of aforesaid chamber 2 and that its other end bears against the bottom of a notch 23 provided for this purpose in aforesaid drum 19.

By means of this combination, in the position of rest of'the fuse, the priming system 11 is automatically and systematically shorted via axis 13, plate 15, collar 16, and rod 17.

The body of the fuse comprises a second rod 26 parallel to aforesaid rod 17 and also having a collar 27 permanently urged by means of a return spring 28.

The part of rod 26 comprised between aforesaid collar 27 and chamber 2 of the fuse body is engaged with an easy fit into the tubular sheath made of insulating material 29 which goes right through aforesaid insulating partition 14 lining the bottom of chamber 3. Aforesaid return spring 28 bears, on the one hand, against aforesaid collar 27 and, on the other hand, against a metal plate 30 which in turn rests against the base 31 made of insulating material, which forms the guiding element of a second part of aforesaid rod 26. The metal plate 30 is directly into contact with the end element 32 into which is engaged and fastened one of the extremities of conductor 33, the other extremity of which is connected to a piezoelectric generator.

By means of this combination, the piezoelectric generator, as long as the fuse is in the position of rest or standby, is short-circuited via the end element 32, the metal plate 30, the return spring 38, the collar 27 the rod 26 and the drum 19 with which the adjacent extremity of aforesaid rod 2 6 is directly into contact through the push exerted on it by the return spring 28.

Onto the rear face 34 of body 1 of the fuse, traversed for instance by aforesaid rod 17, a stud 35 is fastened and serves as support for one of the ends of an elastic strip 36 the other end of which permanently bears against the protruding part of aforesaid rod 17. The latter has, at an appropriate distance, a peripheral groove 37 which is such that, in its drawn-in position, aforesaid rod 17 is locked through the fact that aforesaid strip 36 is engaged into aforesaid peripheral groove 37.

The resulting improved fuse operates as follows: in its position of rest or standby, it looks as illustrated in FIG- URES 1 to 5. Drum 19 is held in its withdrawn position against the action of the elastic element 25 by the corresponding end of rod 17, acting as a bolt. In this position, the priming system 11 and the piezoelectric generator are systematically shorted as indicated before.

Aforesaid priming system 11 remains perfectly immovable, whether the fuse is in the position of rest or cocked.

At the instant of firing, rod 17 is, on account of its inertia, violently projected upward against the action of its return spring 18. The peripheral groove 37 comes to face the elastic strip 36 which systematically locks aforesaid rod or bolt 17 in this Withdrawn posiiton. Drum 19 is thus released from its stop and subjected to the push of spring 24 right to its extreme position (FIGURE 8) caused by the coming into contact of the drum with the corresponding part of the inner wall of body 1 of the fuse. In this position, notch 23 of the drum faces the second rod 26. The latter is thus released from the obstacle formed by the corresponding part of the drum and is almost instantaneously returned by its spring 28 into its locked position of aforesaid drum. 1n the position thereof, the detonator 22 comes to be placed in the axis of the fuse, i.e. also in the axis of the priming system 11.

In this cocked position of the fuse, the preliminary shorts of the priming system and of the piezoelectric generator respectively are open. Indeed, through the fact that rod 17 is locked by the elastic strip 36, the collar 16 has moved away from the metal plate 15 whilst, on account of the withdrawal of drum 19 with respect to rod 26, the contact between the latter elements has been broken.

This being so, the electric fuse, as well as the piezoelectric generator are ready to operate normally as soon as .the projectile has been fired.

It will be noticed that, by means of the combination, the electric connections are actually secured in a positive manner, the mobile element being, in the present instance the detonator, whilst the priming system is fixed.

'It is obvious that the improvements according to the present invention can be embodied in any other way, without exceeding the scope of the invention. The same holds for the electric firing circuit which can be organized in any other appropriate way than that which was mentioned above, whilst the means for displacing and locking the detonator may be any means whatever.

What I claim is:

1. An electric fuse for a projectile having an electric generator, said fuse comprising a hollow housing, a primer fixedly mounted in said housing, a detonator, a support pivotally mounted within said housing and carrying said detonator, an elastic element engaging an inner wall of said housing and said support, said elastic element pressing said support from an inoperative position to an operative position wherein a pyrotechnic chain is established through said generator, said detonator and said primer, a rod slidably mounted in said housing, a second elastic element pressing said rod against said support to maintain said support in said inoperative position, said rod being withdrawn from engagement with said support when the projectile is launched, a second rod slidably mounted in said housing, and a third elastic element pressing the second-mentioned rod against said support to maintain said support in its operative position, the first-mentioned rod short-circuiting said primer when said support is in its inoperative position and removing this short circuit when said support is in its operative position, the second mentioned rod short-circuiting said generator when said support is in its inoperative position and removing this short circuit when said support is in its operative position.

2. An electric fuse for a projectile having an electric generator, said fuse comprising a hollow housing consisting of an electrically conducting material, a primer having a case with opposed open ends and consisting of an electrically conducting material, said case being mounted in said housing and being in electrical contact therewith, and contact means having a portion extending through an open end of said case and consisting of an electrically conducting material; a detonator, a support pivotally mounted within said housing and carrying said detonator, an elastic element engaging an inner wall of said housing and said support, said elastic element pressing said support from an inoperative position to an operative position wherein a pyrotechnic chain is established through said generator, said detonator and said primer, a rod consisting of an electrically conducting material, said rod being slidably mounted in said housing and being in electric contact therewith, a collar carried by said rod, a second elastic element engaging said collar to press said rod against said support to maintain said support in said inoperative position and to move said collar in en-ga-gement with said contact means to short-circuit said primer when said support is in its inoperative position and removing this short circuit when said collar is out of engagement with said contact means, a second rod slidably mounted in said housing, and a third elastic element pressing the second-mentioned rod against said support to maintain said support in its operative position, the second-mentioned rod s-hort-circuiting said generator when said support is in its inoperative position and removing this short circuit when said support is in its operative position.

3. An electric fuse in accordance with claim 2, wherein the first-mentioned rod has a notch, said fuse further having an elastic strip engaging said notch to lock the first-mentioned rod in said inoperative position.

4. An electric fuse for a projecticle, comprising an electrical conductor for the supply of electrical current, a hollow housing consisting of an electrically conducting material, a primer having a case with opposed open ends and consisting of an electrically conducting material, said case being mounted in said housing and being in electrical contact therewith and contact means having a portion extending through an open end of said case and consisting of an electrically conducting material; a detonator, a support consisting of an electrically conducting material, said support being pivotally mounted Within said housing and carrying said detonator, an elastic element engaging an inner wail of said housing and said support, said elastic element pressing said support from an inoperative position to an operative position wherein a pyrotechnic chain is established, a rod consisting of an electrically conducting material, said rod being slidably mounted in said housing and being in electric contact therewith, a collar carried by said rod, a second elastic element engaging said collar to press said rod against said support to maintain said support in said inoperative position and to move said collar in engagement with said contact means to shortcircuit said primer when said support is in its inoperative position and removing this short circuit when said collar is out of engagement With said contact means, a second rod consisting of an electrically conducting material, and slidably mounted in said housing, conducting elements carried by said housing and electrically connecting said electrical conductor With one end of the secondmentioned rod, insulation enclosing a portion of the sec- 10 ond-mentioned rod to insulate it from said housing, and a third elastic element pressing the second-mentioned rod against said support to maintain said support in its operative position.

References Cited by the Examiner UNITED STATES PATENTS 11/1945 Horan 102-78 9/1958 Will et al 10270.2 11/1959 Rabinow 102-702 10/1961 Place et a1 10270.2 X

FOREIGN PATENTS 10/1962 Great Britain.

BENJAMIN A. BORCHELT, Primary Examiner. SAMUEL F-EINBERG, Examiner. W. C. ROCH, Assistant Examiner. 

1. AN ELECTRIC FUSE FOR A PROJECTILE HAVING AN ELECTRIC GENERATOR, SAID FUSE COMPRISING A HOLLOW HOUSING, A PRIMER FIXEDLY MOUNTED IN SAID HOUSING, A DETONATOR, A SUPPORT PIVOTALLY MOUNTED WITHIN SAID HOUSING AND CARRYING SAID DETONATOR, AN ELASTIC ELEMENT ENGAGING AN INNER WALL OF SAID HOUSING AND SAID SUPPORT, SAID ELASTIC ELEMENT PRESSING SAID SUPPORT FROM AN INOPERATIVE POSITION TO AN OPERATIVE POSITION WHEREIN A PYROTECHNIC CHAIN IS ESTABLISHED THROUGH SAID GENERATOR, SAID DETONATOR AND SAID PRIMER, A ROD SLIDABLY MOUNTED IN SAID HOUSING, A SECOND ELASTIC ELEMENT PRESSING SAID ROD AGAINST SAID SUPPORT TO MAINTAIN SAID SUPPORT IN SAID INOPERATIVE POSITION, SAID ROD BEING WITHDRAWN FROM ENGAGEMENT WITH SAID SUPPORT WHEN THE PROJECTILE IS LAUNCHED, A SECOND ROD SLIDABLY MOUNTED IN SAID HOUSING, AND A THIRD ELASTIC ELEMENT PRESSING THE SECOND-MENTIONED ROD AGAINST SAID SUPPORT TO MAINTAIN SAID SUPPORT IN ITS OPERATIVE POSITION, THE FIRST-MENTIONED ROD SHORT-CIRCUITING SAID PRIMER WHEN SAID SUPPORT IS IN ITS INOPERATIVE POSITION AND REMOVING THIS SHORT CIRCUIT WHEN SAID SUPPORT IS IN ITS OPERATIVE POSITION, THE SECOND-MENTIONED ROD SHORT-CIRCUITING SAID GENERATOR WHEN SAID SUPPORT IS IN ITS INOPERATIVE POSITION AND REMOVING THIS SHORT CIRCUIT WHEN SAID SUPPORT IS IN ITS OPERATIVE POSITION. 